Electrochemical <Emphasis Type="Italic">N</Emphasis>-arylation of azoles in MeOH using undivided electrolysis of their mixtures with 1,4-dimethoxybenzene

The reactions of 1,4-dimethoxybenzene with azoles (pyrazole, triazole, and their derivatives, as well as tetrazole) were studied by undivided amperostatic electrolysis at Pt electrodes in MeOH. The process proceeds via the formation of a 1,1,4-trimethoxyarenonium cation as the key intermediate and affords 1,1,4,4-tetramethoxycyclohexa-2,5-diene, 1,1,4-trimethoxy-4-(azol-1-yl)cyclohexa-2,5-diene, and 1,4-dimethoxy-2-(azol-1-yl)benzene as the main products. Azole and solvent molecules compete as nucleophiles during electrolysis. A fine mechanism of the process was considered. Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1166–1171, May, 2005.     

Synthesis and cycloaddition of <Emphasis Type="Italic">N</Emphasis>-substituted pyrroles with polyfluorinated substituents

Reactions of N-pyrrolylpotassium with fluorinated electrophiles yielded N-substituted pyrroles containing polyfluoroalkyl, polyfluoroalkenyl, polyfluoroalkylsulfonyl, and polyfluoroaryl substituents. N-Polyfluoro-substituted pyrroles did not isomerize at ≥100 °C; they were found to be reactive in [4+2] cycloaddition reactions with perfluorobut-2-yne. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1890–1895, August, 2005.     

Synthesis of isomeric 2-oxazolidinones from (1<Emphasis Type="Italic">R</Emphasis>,2<Emphasis Type="Italic">R</Emphasis>)-and (1<Emphasis Type="Italic">S</Emphasis>,2<Emphasis Type="Italic">S</Emphasis>)-2-amino-1-(4-nitrophenyl)-1,3-propanediols

A synthesis is reported for (4R,5R)-and (4S,5S)-4-hydroxymethyl-5-(4-nitrophenyl)oxazolidin-2-ones and (1′R,4R)-and (1′S,4S)-4-[hydroxy(4-nitrophenyl)methyl]oxazolidin-2-ones from (1R,2R)-and (1S,2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediols. The effect of the experimental conditions on the formation of these compounds was studied. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1562–1570, October, 2007.     

3,3,3-Trifluoro-<Emphasis Type="Italic">N</Emphasis>′-(3-trifluoromethylphenyl)-1,2-propanediamine and its <Emphasis Type="Italic">N</Emphasis>-mono-and <Emphasis Type="Italic">N,N</Emphasis>-dicarboxyethyl derivatives: synthesis,protolytic and complexation properties

3,3,3-Trifluoro-N′-(3-trifluoromethylphenyl)-1,2-propanediamine (5) was synthesized by the reaction of 2-diazo-1,1,1-trifluoro-3-nitropropane or 3,3,3-trifluoro-1-nitropropene with 3-aminobenzotrifluoride followed by the reduction of the nitro group. The Michael 1,4-addition of diamine 5 to acrylic acid occurs only at the N(1) atom and affords N-mono-or N,N-dicarboxyethyl derivatives 6 and 7, depending on the reactant ratio. Protolytic equilibria 5–7 in aqueous solutions were studied by pH-potentiometry and UV spectroscopy. Only the aliphatic amino group can be protonated in an aqueous solution, while the aromatic amino group remains unprotonated even in 12 M HCl. The stability constants of transition metal (Cu²⁺, Ni²⁺, Zn²⁺) complexes with ligands 5–7 were determined by pH-potentiometric titration. The stability of the complexes and selectivity of the ligands toward Cu²⁺ ions increase with an increase in the number of N-carboxyethyl groups. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2465–2469, November, 2005.     

<Emphasis Type="Italic">O</Emphasis>- and <Emphasis Type="Italic">N</Emphasis>-Alkylation of <Emphasis Type="Italic">N</Emphasis>-halosuccinimides in ionic reactions with 1-phenyltricyclo [4.1.0.0<Superscript>2,7</Superscript>]heptane

N-Bromo and N-chlorosuccinimides add to 1-phenyltricyclo[4.1.0.0^2,7]heptane in CH₂Cl₂ with cleavage of the C(1)-C(7) bond to give isomeric 1 : 1 Markownikoff-type endo, anti-adducts of the norpinane structure in a ∼3 :7 ratio corresponding to N and O alkylation of succinimide.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No.2, pp. 457–460, February, 2005     

Effect of type and concentration of surfactants on swelling behavior of poly[<Emphasis Type="Italic">N</Emphasis>-[3-(dimethylamino)propyl]methacrylamide-co- <Emphasis Type="Italic">N,N</Emphasis>-methylenebis(acrylamide)] hydrogels

A series of thermosensitive hydrogels were prepared from N-[3-(dimethylamino)propyl]methacrylamide (DMAPMA) monomer by using 11.6–17.8% (m/m) N,N-methylenebis(acrylamide) (MBAAm) as the crosslinker and comonomer in water. A kinetic study of the absorption determined the transport mechanism. The diffusion coefficients of these hydrogels were calculated for the Fickian mechanism. It was shown that the swelling behavior of the P(DMAPMA-co-MBAAm) hydrogels can be controlled by changing the amount of MBAAm. The swelling equilibrium of the P(DMAPMA-co-MBAAm) hydrogels was also investigated as a function of temperature in aqueous solutions of the anionic surfactant sodium dodecyl sulfate (SDS) and the cationic surfactant dodecyltrimethylammonium bromide (DTAB). In pure water, irrespective of the amount of MBAAm, the P(DMAPMA-co-MBAAm) hydrogels showed a discontinuous phase transition between 30 and 40 °C. However, the transition changed from discontinuous to continuous with the addition of surfactants, this is ascribed to the conversion of non-ionic P(DMAPMA-co-MBAAm) hydrogel into polyelectrolyte hydrogels due to binding of surfactants through the hydrophobic interaction. Additionally, the amount of free SDS and DTAB ions was measured at different temperatures by a conductometric method, it was found that the electric conductivity of the P(DMAPMA-co-MBAAm) – surfactant systems depended strongly on both the type and concentration of surfactant solutions.     

Synthesis and structure of <Emphasis Type="Italic">N</Emphasis>-(2-(1-adamantyl)-2-hydroxyethyl)cytisine diastereomers

Diastereomers of N-(2-(1-adamantyl)-2-hydroxyethyl)cytisine were synthesized by reduction of N-(2-(1-adamantyl)-2-oxoethyl)cytisine with NaBH₄. Their structures were established using x-ray structure analysis. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 244–247, May–June, 2007.     

Synthesis and biological activity of <Emphasis Type="Italic">N</Emphasis>-(2-hydroxyethyl)cytisine derivatives

Derivatives of N-(2-hydroxyethyl)cytisine, N-(2-hydroxypropyl)-, N-(2-hydroxy-2-(1-adamantyl)ethyl)-, and N-(2-hydroxy-2-phenylethyl)cytisine, were synthesized by reduction of N-(2-oxopropyl)-, N-(2-oxo-2-(1-adamantyl)ethyl)-and N-(2-oxo-2-phenylethyl)cytisine with metal hydrides. The antiarrhythmic and analgesic activities of the prepared compounds were investigated. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 157–162, March–April, 2007.     

Synthesis and Pharmacological Evaluation of Chlorinated <Emphasis Type="Italic">N</Emphasis>-Alkyl-3- and -5-(2-hydroxyphenyl)pyrazoles as <Emphasis Type="Italic">CB</Emphasis><Subscript>1</Subscript> Cannabinoid Ligands

Summary. The syntheses of several new 3- and 5-(4-chloro-2-hydroxyphenyl)-5- and -3-(2,4-dichlorophenyl)-1-alkylpyrazoles are reported. These syntheses started from simple chlorophenols, 2,4-dichlorobenzaldehyde or ethyl 2,4-dichlorobenzoate in order to prepare pyrazoles bearing three and four chloro substituents in certain positions. The affinity of these compounds towards the CB ₁ type cannabinoids receptors was then evaluated in human brain tissues (frontal cortex). The results showed that some of the compounds exhibit affinity towards this kind of receptors in the micromolar range.     

Ethylenebis(<Emphasis Type="Italic">N</Emphasis>-methylimidazolium) Chlorochromate (<Emphasis Type="Italic">EBMICC</Emphasis>): An Efficient and Selective Reagent for the Oxidation of Thiols to Disulfides

Summary. Ethylenebis(N-methylimidazolium) chlorochromate was prepared by addition of N-methylimidazole to 1,2-dibromoethane to form the corresponding dibromide salt and subsequent treatment of this salt with CrO₃ in 6N HCl solution. It is a stable yellow-orange solid, which oxidized thiols to the corresponding disulfides at room temperature. Selective oxidation of thiols in the presence of sulfides and hydroxyl groups was also achieved with this reagent.     

<Emphasis Type="Italic">tert</Emphasis>-Butyl (2<Emphasis Type="Italic">S</Emphasis>)-(<Emphasis Type="Italic">p</Emphasis>-tolylsulfonyloxy)propionate — a suitable reagent for the direct alkylation of indole derivatives

A new method is proposed for the synthesis of indole derivatives containing a chiral substituent at the nitrogen atom, which includes the direct alkylation of indole derivatives with tert-butyl (2S)-(p-tolylsulfonyloxy)propionate, obtained from commercial ethyl (S)-lactate with subsequent conversion to the corresponding p-toluenesulfonyloxy derivative by hydrolysis, and esterification. Dedicated to Academician B. A. Trofimov on his 70^th birthday. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, 1391–1398, September, 2008.     

<Emphasis Type="Italic">N</Emphasis>-(3-Phosphonopropyl)-substituted α-amino acids and their phosphine oxide analogs

A facile method was developed for the synthesis of N-(3-phosphonopropyl)-substituted α-amino acids and their phosphine oxide analogs based on hydrolysis of 2-oxo-1,2-azaphospholanes and 1,2-azaphospholanium salts prepared from readily available reagents. A chelate Cu^II N-[(3-diphenylphosphoryl)propyl]glycinate was isolated. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2551–2556, November, 2005.     

Oxidation of α-methylstyrene on an MCM-22 encapsulated (<Emphasis Type="Italic">R,R</Emphasis>)-(−)-<Emphasis Type="Italic">N,N′</Emphasis>-bis(3,5-di-<Emphasis Type="Italic">tert</Emphasis>-butylsalicylidene)-1,2-cyclohexanediaminocobalt(II) catalyst

(R, R)-(−)-N, N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminocobalt(II) was encapsulated into MCM-22 using the zeolite synthesis method. The encapsulated catalyst proved to be active in the oxidation of α-methylstyrene with NaOCl with higher specific activity than the homogeneous catalyst. At the same time, this encapsulated catalyst was completely inactive in the hydrolytic kinetic resolution of racemic styrene oxide. This observation is in a good correlation with the assumption of the cooperative bimetallic mechanism proposed by Annis and Jacobsen.     

Structure and photochromism of 2-(<Emphasis Type="Italic">N</Emphasis>-acyl-<Emphasis Type="Italic">N</Emphasis>-arylaminomethylene)benzo[<Emphasis Type="Italic">b</Emphasis>]thiophen-3(2<Emphasis Type="Italic">H</Emphasis>)-ones

It was shown by electron absorption spectroscopy and X-ray diffraction analysis that steric strains in photochromic 2-(N-acyl-N-arylaminomethylene) benzo[b]thiophen-3(2H)-one molecules ortho-substituted in the N-phenyl ring increase the quantum yield of the N→O photoinduced rearrangement in accord with an increase in the steric constant of the ortho-substituent.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2151–2155, October, 2004.     

Chemistry of <Emphasis Type="Italic">N,N</Emphasis>-bis(silyloxy)enamines 7. Quaternization of tertiary amines and nitrogen-containing heterocycles by <Emphasis Type="Italic">N,N</Emphasis>-bis(silyloxy)enamines

Coupling of N,N-bis(silyloxy)enamines with tertiary amines and nitrogen-containing heterocycles affording the corresponding functionalized ammonium or iminium salts was studied. The area of its application was determined, and optimal procedures for the synthesis of the target products were proposed. The mechanism including the formation of conjugated nitroso alkene or a silylnitrosonium cation as key intermediates is discussed.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2137–2143, October, 2004.     

Chemical properties of <Emphasis Type="Italic">N</Emphasis>-polyfluoroethylimidazole and -pyrrole derivatives

Bromination, acylation, nitration, and metallation of imidazole and pyrrole derivatives containing the difluoromethylene fragment at the N atom were studied. 1-(1,1,2,2-Tetrafluoroethyl)pyrrole, 1-(1,1,2,2-tetrafluoroethyl)imidazole, and 1-(2-chloro-1,1,2-trifluoroethyl)imidazole were used as substrates. 1-Alkyl-3-(1,1,2,2-tetrafluoroethyl)- and 1-alkyl-3-(2-chloro-1,1,2-trifluoroethyl)imidazolium iodides were obtained. These can be used as intermediates for preparation of new ionic liquids of the imidazole series and 1-alkyl-3-polyfluoroethylimidazole-2-thiones.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 781–787, March, 2005.     

Synthesis of poly(<Emphasis Type="Italic">N</Emphasis>-methylolacrylamide)/polymethylacrylamide hybrids via frontal free-radical polymerization

In this study, poly(N-methylolacrylamide)/polymethylacrylamide (PNMA/PMAA) hybrids were produced successfully by frontal free-radical polymerization at ambient pressure. In a typical run, the appropriate amounts of reactants (N-methylolacrylamide, NMA; methylacrylamide, MAA) and initiator (ammonium persulfate) were dissolved in dimethyl sulfoxide at ambient temperature. Frontal polymerization (FP) was initiated by heating the wall of the tube with a soldering iron, and the resultant hot fronts were allowed to self-propagate throughout the reaction vessel. Once initiated, no further energy was required for polymerization to occur. The dependences of the front velocity and front temperature on the initiator concentration, reactant dilution, and NMA/MAA components were thoroughly investigated. The front temperatures were between 69 and 116 °C, depending on the persulfate concentration. We have also investigated the FP of PNMA/PMAA hybrids with N-methyl-2-pyrrolidone as solvent. Results show that FP can be exploited as a means for the preparation of PNMA/PMAA hybrids with the potential advantage of higher throughput compared to the traditional mode.     

A study of influence of temperature and <Emphasis Type="Italic">N</Emphasis>, <Emphasis Type="Italic">N</Emphasis>-acyl protected keto ylides structure on their predominant transformations

The effect of temperature and keto ylides structure on preference of their intramolecular cyclization leading to N-containing heterocyclic compounds or linear products formation has been investigated at the B3LYP/6-31G(d,p) level of theory. It has been determined that the thermodynamic advantage of the cyclization reactions of ylides increases with temperature, while Gibbs free energies of linear products formation reactions depend insignificantly on temperature. The Wittig and the Corey–Chaykovsky reactions are least probable in the case of the sulfonium and ammonium ylides considered. However, for phosphonium ylides the Wittig reaction must be considerably preferable in comparison with other routes, while behavior of the arsonium ylides is predicted to be more complex. Research of S-ylides transformations shows that formation of methylthio-substituted heterocycles with five-, six- or seven- membered rings is possible from a thermodynamic standpoint, while conversion of the corresponding ylide to a four-membered heterocycle is disadvantageous. Presence of a methyl substituent and its position in the ylide carbon chain depends ambiguously on the behavior of sulfur keto ylides.     

<Emphasis Type="Italic">N</Emphasis>-Bromoacetyl-β-<Emphasis Type="SmallCaps">D</Emphasis>-glycopyranosylamines in the synthesis of glycoconjugates of nitrogen-containing physiologically active compounds

A series of nitrogen-containing physiologically active compounds underwent smooth N-monoalkylation with N-bromoacetyl-β-glycopyranosylamines derived from N-acetyl-D-glucosamine and lactose. This reaction was demonstrated to be promising for the introduction of carbohydrate residues into heterocyclic compounds, viz., pyridine, imidazole, pyrimidinetrione, carboline, and piperazine derivatives, and into an amino acid, 5-hydroxy-L-tryptophan, which is unstable in alkaline media. Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1256–1259, May, 2005.     

Reactions of 3-nitro-2-trihalomethyl-2<Emphasis Type="Italic">H</Emphasis>-chromenes with indole, <Emphasis Type="Italic">N</Emphasis>-methylindole,and <Emphasis Type="Italic">N</Emphasis>-methylpyrrole. Stereoselective synthesis of 4-azolyl-3-nitro-2-trihalomethylchromanes

Heating of 3-nitro-2-trifluoromethyl-and 3-nitro-2-trichloromethyl-2H-chromenes with indole, N-methylindole, and N-methylpyrrole under solvent-free conditions led with high stereoselectivity and in good yields to cis-trans-3-nitro-2-trifluoromethyl-or trans-cis-3-nitro-2-trichloromethylchromanes substituted by the indol-3-yl (pyrrol-2-yl) fragment in position 4. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1985–1990, October, 2007.